upgrading to v4, change of "req.backend.healthy" -> "std.healthy(req.backend)" reports "Symbol not found: 'std.healthy' (expected type BOOL)"

[grantksupport at operamail.com]

I added the 

  import std;

now, at VCL check of my 'full' vcl, I get simply

 /usr/local/sbin/varnishd -n TEST -C -f
 /usr/local/etc/varnish/vcl.TEST.conf
  Running VCC-compiler failed, exit 1
  
  VCL compilation failed

no further info on WHY ...

yet.

Grant